Securing mechanically stressed constructional members to wooden supports



Dec. 22; 1953 F. GRAF ET AL SECURING MECHANICALLY STRESSED CONSTRUCTIONAL MEMBERS TO WOODEN SUPPORTS Filed July 25, 1951 FIG. v 7

FIG. 2 a 5 dw'liilf'y/l JNVENTOR. F R IT Z G R A F a-vk L 1 ATT Y5 Patented Dec. 22, 1953 UN ITED STATE-S EATENT OFFICE 2,663,662r SECURING MECHANTCAIZIZY' STRESSED' GON STRUCTIQN AL ME S T WOGDEN SUPPOETS' Fritz Graft Ludwigshafen Germany;

assignorsp to Badisoliei (Rhine.),, and (Rhine-Qggersheim A'nili n- &

Soda-Fabrilt Aktiengesellsohaft Ludwigsliafen am" Rhine; Rheihlan Germany imdesrepuhiilh ApplicationJuly 25;; 1951, serialrNoh 238,58&

Germany:

AIlig-ust 26, 1950 4. Claims. Cl. 15.49-11.91)

invention relates; to. a method or securing mechanically stressed constructional. members to; wooden.- supports;

The. securing of. constructional. parts; usually at iron, are; subieoted. to strong: mechani-- cal: stress, towooden: supports; whic isrmainl-sr effected by; means of? screws, is; often: unsatisfiac.-. tory because the screws; gradually beeorna loose inthe-wood. Thfi'WOOdE in the neighbourhood tha screwthreads is gradually broken by the:

thrust, and. pull: so that; the screws no: longerhave any hold. Resorewing may a, certain strengthening, but t lie-is onlyof short duration. The, parts of; the wood ata distancefrom: thescrews. are usuallysubiected; to: tar

lessstress. The same-is. truaforsecuring; means;

other than. screwsas. for. example. r-I-a-ils and-bolts We have new-found that a durableconnection. between such constructional parts; and: wooden: supports can be obtained by providing holes closed at, oneend, in the. wood for. the: securing means, particular screws; filling the holes; with a low molecular weight condensationproduet; oi a diurethaneand; formaldehyde, and introducing the securing'means before the condensation product is hardened out.

A. method in accordance with the invention: is illustrated in the. attached drawing wherein:

Figure 1 is a sectional View of parts in the process of being connected inaccordance: with one embodiment of the invention; and

Figure 2 is a sectional-view or the connected parts.

In the drawing, a wooden tie t is represented and a hole 2 bored therein. A condensation product 3- of a diurethane and formaldehyde in a fluid state is provided in the hole. A metal tie plate 4) is positioned against; the wooden tie i1, and a screw spiked is inserted in -ca hol'eriau the tie plate above the hole 2 in the tie. The spike 5 is screwed into the tie I, thereby forcing the condensation product 3 into the tie in the area surrounding the tie hole 2, resulting in the assembly shown in Figure 2. Due to the pressure exerted on the condensation product 3, it penetrates the tie I for a distance, forming an impregnated area 6 surrounding the tie hole 2. On hardening, a correspondingly strengthened area is present in the tie forming a strong, elastic and water insoluble seat for the spike 5.

The diurethanes; rear for the preparation of: the hardenablae: condensation products or dimethanesv and formaldehyde may obtained" for example by fusing dihydric alcohols: ir urea or: by; the: reaction or: chlbrocarbonic acid esters Mixtures or the pr i 1 obtained may also be used. Condensat i ucts which have been obtained by heating equivalent amounts of a dipritn-ary alcohol and urea until about 40 to of diure-thane have been fer-med and reacting the re 'ul'ting melt with fermald'ehyd'e have proved especiallyadvanta geous. Suitable alcohols are for exarnpieydi primary alcohols; such as propane die-1&3; tanediol-IA, pen-ta-ne diol-l-Lfi; hexane dict-i261 d-ietliylen-e glycol and higher polyethylene glycol's', dihydroxydibutyr ether; dihydrcxydiethyl sulfide, and also: d ihydri'o secondary alcoheis; such as 1.3 or ZB-buty-lene glycol; Small amounts of; higher" polyhydrio alcohols; such as glyceriiie', vtri? nrethyl olpropane, hexane triol and erythrit'ol', may also be'ememployed for the production of condensation products: Mixturesof said alcohols are also-suitable. 7

Usually it is: preferable to co-emp'loy acid" condensi-ngt agents: orcondensing agents whi'ch' split; on. acid, order to convert the condensation product's: introduced into the wood, without the employment of heat; into a higher-molecular; elastic; wateri-nsolublecondition" in which efiect the strengthening of the Wood lying in the neighbourhoodsurrounding the sore vantageous to employfor thisjpurpose acid-reacting condensing agents; which. at the sametime, effect an, improvement, in the surface, at iron: se curing.means,,such as: screws. or the like: Ehoa phoric acid anditsacid-reacting compounds; areespecially suitable because on: the.-

hand

have such a slow hardening action on the condensation products from diurethanes and formaldehyde that they may be conveniently worked for a long time, i e. pressed into the neighbourhoodof the screw holes, and on the other hand they produce on the iron screws or the like pressed into the wood a phosphate layer which is considerably more stable to corrosion than the original iron surface.

Other substances, such as dyestuffs, tar oils. wood preserving agents and the like, may also be 15., is, ada incorporated with the said condensation products.

The introduction of the said condensation products from diurethanes and formaldehyde into the surroundings of the screws and the like to be introduced is preferably effected as follows:

Holes are bored in the wooden support for the reception of the screws and the like which are later to be inserted; these holes preferably do not pass right through the support, but only to such an extent that one end remains closed. A measured amount of the said condensation products is introduced into these holes. The constructional part to be mounted on the wooden support is then brought into its appointed place and the screws or the like by which it is to be fixed are inserted or screwed into the holes filled with condensation product. There is thus produced within the holes a pressure which is so strong that the condensation product present in the holes is forced into the wood surrounding the screws or the like and thoroughly impregnates the same. The screws or the like are then located in a wood which has improved mechanical properties in the parts surrounding the screws or the like after the condensation product has been hardened. The constructional part thus mounted on the wooden support is satisfactorily secured for a long period.

The following example will further illustrate this invention but the invention is not restricted to this example.

Example A beechwood railway sleeper 15 centimetres in thickness is bored at the appropriate places so that the holes, corresponding to the length of the screws to be inserted, extend only about centimetres into the wood. The holes are filled with the aid of a grease gun with a condensation product from diurethanes and formaldehyde which has been mixed with 1% of concentrated phosphoric acid. The rail bed plates are then laid on the sleeper and the rail screws inserted into the filled holes and screwed in. By the screwing in of the screws, the condensation product is forced into the wood to the extent of a few millimetres, whereupon it becomes condensed out and water insoluble. Contrasted with untreated wood, the wood thus impregnated has a considerably greater thrust resistance and bending strength, and is very resistant to mechanical stresses transmitted thereto by the screws, such as are caused by the loading with the rails and the forces exerted thereon.

The condensation product from diurethane and formaldehyde employed is prepared as follows:

540 parts of butanediol-1,4 are heated with 756 parts of urea at 170 C. under a pressure of 80 to 150 millimetres (mercury gauge) for 3 hours. To complete the reaction, the whole is then kept at 170 C. for another hour. 1500 parts of aqueous 30% formaldehyde are added to the melt while it is still hot, and the whole is then heated under reflux for about 3 hours.

What we claim is:

1. A process for effecting a durable connection between a mechanically strongly stressed constructional part and a wooden part with the aid of securing means which comprises providing in said wooden part a hole closed at one end for the close reception of said securing means, introducing a condensation product of a diurethane and formaldehyde into said hole in a fluid state, inserting said securing means into said hole and thereby forcing said condensation product into said wooden part in the area surrounding said hole, concomitantly engaging said constructional part and said securing means, and hardening said condensation product.

2. The process according to claim 1 in which a condensation product of formaldehyde and the diurethane of butanediol-1,4 is employed.

3. A process for effecting a durable connection between a mechanically strongly stressed constructional part and a wooden part with the aid of securing means which comprises providing in said wooden part a hole closed at one end for the close reception of said securing means, introducing a condensation product obtained by heating a di-primary alcohol and urea until about 40% to 70% of diurethane has been formed and reacting the resulting melt with formaldehyde into said hole in a fluid state, inserting said securing means into said hole and thereby forcing said condensation product into said wooden part in the area surrounding said hole, concomitantly engaging said constructional part and said securing means, and hardening said condensation product.

4. A process for durably connecting a wooden part and a metallic securing member which comprises providing in said wooden part a hole closed at one end for the close reception of said securing member, introducing a condensation product of a diurethane and formaldehyde into said hole in a fluid state, inserting said securing member into said hole and thereby forcing said condensation product into said wooden part in the area surrounding said hole, and hardening said condensation product.

FRITZ GRAF. TIM TOEPEL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 731,928 Mattice June 23, 1903 1,997,803 Miller Apr. 16, 1935 2,040,126 Grieve May 12, 1936 2,389,464 Snyder Nov. 20, 1945 2,395,300 Slauson Feb. 19, 1946 FOREIGN PATENTS Number Country Date 491,449 Great Britain Sept. 1, 1938 

1. A PPROCESS FOR EFFECTING A DURABLE CONNECTION BETWEEN A MECHANICALLY STRONGLY STRESSED CONSTRUCTIONAL PART AND A WOODEN PART WITH THE AID OF SECURING MEANS WHICH COMPRISES PROVIDING IN SAID WOODEN PART A HOLE CLOSED AT ONE END FOR THE CLOSE RECEPTION OF SAID SECURING MEANS, INTRODUCING A CONDENSATION PRODUCT OF A DIURETHANE AND FORMALDEHYDE INTO SAID HOLE IN A FLUID STATE, IN- 